The spherical harmonics Y[lm](theta,phi) is reduced to a simple
Legendre function p[l](cos(theta)) scaled by a constant when m=0,
which is independent of phi. The following equations and figure are
Y[l](theta) for several l-values.

Using this Y[l](theta) with l=lambda=even terms, shape of a deformed
nucleus can be expanded as follows:

where the beta a parameter of deformation. If beta=0, the nucleus is
spherical. The 3-dim. shape given by this equation is shown with
gnuplot. As it is already shown in the previous section, we express the (x,y,z)
coordinate with the angles u,v and radius r.

where the theta is the angle measured from the Z-axis, so that the relation
between theta and v is theta = pi/2-v. To draw the surface,
the parameters u,v are varied from 0 to 360 deg. In the case of
beta_2 = 0.3, beta_4 = 0.1, and R_0 = 1:

The deformation parameters, beta_2 and beta_4 can be positive or
negative. Here are some examples for some combinations of beta_2
and beta_4. The beta_2 parameters are taken to be -0.4 or 0.4, and
for each beta_2, we changed the beta_4 value from -0.2 to 0.2. When
beta_2 is positive the shape of nucleus is prolate, while it
becomes oblate if beta_2 is negative.